While there is little or no radar in oceanic regions, there occur a vast number of flights over such regions. For example, on a typical day, hundreds of flights cross the North Atlantic, most of which operate on standard routes. In addition to a large number of aircraft operating in an oceanic environment, the majority of flights occur during a relatively small time window primarily due to airline requests to accommodate destination airport curfew restrictions and customer convenience. Thus, many flights operate on similar routes around the same time resulting in local congestion.
Since most flights are made by similar aircraft, there is a large demand for similar crossing altitudes. The result is that some aircraft must fly at other than optimal altitudes, possibly resulting in fuel inefficiency. While there are aircraft that would occasionally climb or descend to more optimum altitudes during an oceanic crossing, such transitions are made difficult by (1) large separation requirements, and (2) limited local surveillance for identifying spaces at more desirable altitudes into which an aircraft could climb or descend.
Automatic Dependent Surveillance Broadcast (ADS-B) is a surveillance technique based on the capability of aircraft to automatically and periodically transmit data such as position, altitude, velocity, and aircraft identification. The information can be received by ground stations and other aircraft. It is precise because it relies on a GPS source and has a high refresh rate thus providing improved traffic awareness in the cockpit.
Through the use of ADS-B and ITP procedures, altitude changes are enabled that were previously blocked due to current aircraft separation minima standards; the standard separation is required between all aircraft at the current desired altitudes. The result is reduced fuel burn and CO2 emissions because ITP enables aircraft to achieve flight level changes more frequently because ITP permits climbs and descents using new reduced longitudinal separation standards.
Aircraft traffic is displayed on a cockpit plan mode display and on a vertical profile display referred to as an ITP display. A pilot may plan an ITP clearance procedure (climb or descend) by viewing traffic intruders (blocking aircraft and candidate reference aircraft) on the ITP display. A blocking aircraft is one that is between the initial and desired flight levels that blocks a standard procedural level change. Reference aircraft may be one or two aircraft transmitting valid ADS-B data that meets ITP criteria and is identified to Air Traffic Control (ATC) by the aircraft considering a flight level change as part of the ITP clearance request. However, the ITP display shows only similar track traffic intruders equipped with ADS-B OUT and transmitting ADS-B OUT data within prescribed navigational accuracy limits. If the ADS-B OUT data of the traffic intruder has dropped off for some reason or has navigational accuracy (e.g. position, vertical velocity) parameters that fall below prescribed limits, the intruder will not be represented on the ITP vertical profile display and are considered as degraded traffic. In addition, pure TCAS (Traffic Collision Avoidance System) intruders that are either blocking (an aircraft that is between the initial and desired flight levels and blocks a standard procedural level change) or non-blocking will not be represented on the ITP display.
Considering the foregoing, it would be desirable to provide an aircraft display system and method for displaying intruder aircraft exhibiting navigational accuracy parameters below prescribed limits (i.e. navigational uncertainty) in the ITP display. It is also desirable to provide an aircraft system and method for displaying ADS-B equipped intruder aircraft whose ADS-B data has dropped off. It is further desirable to provide an aircraft display system and method for displaying intruder aircraft not equipped with ADS-B but equipped with TCAS alone. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the appended claims taken in conjunction with the accompanying drawings and this background of the invention.